Comparative Study Between Mixed Dyeing of Wool Fiber in One and Two Dye Baths with Natural Indigo and Madder Colorants

Abstract

The objective of the present study was to compare between the mixed dyeing of wool fiber in one and two dye baths using natural indigo (Indigofera tinctoria) and madder colorants (Rubia tinctorum). Based on the reduction and oxidation reaction conditions under the same dyeing mechanism for the indigo and madder colorants, the exhaustion rate of the mixed dyeing in two dye baths was higher than that for mixed dyeing in one dye bath. The poor exhaustion rate that was achieved when dyeing in a single dye bath indicated the incompatibility of both dyes when mixed in one dye bath. However, both methods achieved a rigid fixation as confirmed by washing-fastness test 105C6A01.